the above file contains no info and when I try and open it says new file. So do I create files that do not exist. as I ran the command prior to the above. I used webmin to add users. Again I am using just local or system users no virtual users

"etc/postfix/local-host-names"
"etc/postfix/local-host-names" E212: Can't open file for writing
Hit ENTER or type command to continue
Get a 127 Shell error as well
Any ideas on why I can not create this file

Again the users were created in webmin
Here is the error message I got

root@mail:~# postmap /etc/postfix/virtusertable
postmap: warning: /etc/postfix/virtusertable.db: duplicate entry: "sample.net"
postmap: warning: /etc/postfix/virtusertable.db: duplicate entry: "sample.net"
postmap: warning: /etc/postfix/virtusertable.db: duplicate entry: "sample.net"
is this not needed since I created the users in webmin or should I delete all users out of webmin and then create them manually?

I got the above waring/error when I added another user (I created the user in webmin first) and then added to the virtusertable
The following file exist but nothing is in it
/etc/postfix/main.cf